1. Field of the Invention
This invention relates to retractable propellers, for example to such which are shown in my U.S. Pat. No. 4,136,145 but at the same time to propellers which can vary their pitch.
2. Description of the Prior Art
In my U.S. Pat. No. 4,136,145 a two bladed propeller is shown which can swing its blades forward and can then be retracted into the wing or body of a fluid borne craft. From the motor glieders it is known, that the pitches of two bladed propellers can be set into a "zero" position at which their chords are substantially equally directed to the flight path of the aircraft.